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Molecular mechanisms of action of herbal antifungal alkaloid berberine, in Candida albicans.

Dhamgaye S, Devaux F, Vandeputte P, Khandelwal NK, Sanglard D, Mukhopadhyay G, Prasad R - PLoS ONE (2014)

Bottom Line: However, unlike BER, HSF1 effect on CW appeared to be independent of MAP kinase and Calcineurin pathway genes.Additionally, unlike hsf1 strain, BER treatment of Candida cells resulted in dysfunctional mitochondria, which was evident from its slow growth in non-fermentative carbon source and poor labeling with mitochondrial membrane potential sensitive probe.Together, our study not only describes the molecular mechanism of BER fungicidal activity but also unravels a new role of evolutionary conserved HSF1, in MDR of Candida.

View Article: PubMed Central - PubMed

Affiliation: School of Life Sciences, Jawaharlal Nehru University, New Delhi, India; Special Centre for Molecular Medicine, Jawaharlal Nehru University, New Delhi, India.

ABSTRACT
Candida albicans causes superficial to systemic infections in immuno-compromised individuals. The concomitant use of fungistatic drugs and the lack of cidal drugs frequently result in strains that could withstand commonly used antifungals, and display multidrug resistance (MDR). In search of novel fungicidals, in this study, we have explored a plant alkaloid berberine (BER) for its antifungal potential. For this, we screened an in-house transcription factor (TF) mutant library of C. albicans strains towards their susceptibility to BER. Our screen of TF mutant strains identified a heat shock factor (HSF1), which has a central role in thermal adaptation, to be most responsive to BER treatment. Interestingly, HSF1 mutant was not only highly susceptible to BER but also displayed collateral susceptibility towards drugs targeting cell wall (CW) and ergosterol biosynthesis. Notably, BER treatment alone could affect the CW integrity as was evident from the growth retardation of MAP kinase and calcineurin pathway mutant strains and transmission electron microscopy. However, unlike BER, HSF1 effect on CW appeared to be independent of MAP kinase and Calcineurin pathway genes. Additionally, unlike hsf1 strain, BER treatment of Candida cells resulted in dysfunctional mitochondria, which was evident from its slow growth in non-fermentative carbon source and poor labeling with mitochondrial membrane potential sensitive probe. This phenotype was reinforced with an enhanced ROS levels coinciding with the up-regulated oxidative stress genes in BER-treated cells. Together, our study not only describes the molecular mechanism of BER fungicidal activity but also unravels a new role of evolutionary conserved HSF1, in MDR of Candida.

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Model depicting pathways affected by BER treatment in C. albicans.
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pone-0104554-g007: Model depicting pathways affected by BER treatment in C. albicans.

Mentions: In this study, we show that the plant alkaloid BER displays potential anti-Candida activity which has been earlier reported to be non-toxic to humans [26] Our data supports that HSF1, a transcription regulator that is an essential gene involved in thermal adaptation of Candida cells, impacts BER susceptibility of C. albicans cells. HSF1 protects cells from thermal assault by activating the expression of HSPs (Heat Shock Proteins) that act as chaperones to rescue proteins from misfolding under duress [19]. Our observation suggests that HSF1, which not only impacts BER susceptibility, also influences susceptibility of Candida cells to different drugs with distinct targets. Thus HSF1 mutant is also observed to be collaterally susceptible to other drugs (Figure 3(b)). However, the impact of BER and HSF1 on drug susceptibility is manifested by independent pathways in Candida cells. Our conclusions are based upon the following supporting observations. The treatment of TF mutant strains of Candida cells with BER revealed that HSF1 mutant was most susceptible to this antifungal compound. BER treatment affects the calcineurin pathway and CW integrity leading to dysfunctional mitochondria and cell death. HSF1 levels also impact CW integrity, which is apparent from the susceptibility of HSF1 conditional mutants towards CW inhibitors and from disrupted CW visualized under TEM images. However, unlike BER treatment, the impact of HSF1 on CW integrity was independent of calcineurin stress pathway. For example, neither HSF1 levels could affect the expression of calcineurin pathway genes nor observed dysfunctional mitochondria and enhanced ROS levels following BER treatment were associated with HSF1 phenotype. Although, HSF1 levels potentiate the antifungal activity of BER but its influence in enhancing drug susceptibility adopts different regulatory circuitry as shown in Figure 7. Together, our results show that BER displays its antifungal potential through its ability to impair mitochondrial function, generation of ROS, targeting CW integrity pathway and also affecting heat shock transcription factor HSF1.


Molecular mechanisms of action of herbal antifungal alkaloid berberine, in Candida albicans.

Dhamgaye S, Devaux F, Vandeputte P, Khandelwal NK, Sanglard D, Mukhopadhyay G, Prasad R - PLoS ONE (2014)

Model depicting pathways affected by BER treatment in C. albicans.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4126717&req=5

pone-0104554-g007: Model depicting pathways affected by BER treatment in C. albicans.
Mentions: In this study, we show that the plant alkaloid BER displays potential anti-Candida activity which has been earlier reported to be non-toxic to humans [26] Our data supports that HSF1, a transcription regulator that is an essential gene involved in thermal adaptation of Candida cells, impacts BER susceptibility of C. albicans cells. HSF1 protects cells from thermal assault by activating the expression of HSPs (Heat Shock Proteins) that act as chaperones to rescue proteins from misfolding under duress [19]. Our observation suggests that HSF1, which not only impacts BER susceptibility, also influences susceptibility of Candida cells to different drugs with distinct targets. Thus HSF1 mutant is also observed to be collaterally susceptible to other drugs (Figure 3(b)). However, the impact of BER and HSF1 on drug susceptibility is manifested by independent pathways in Candida cells. Our conclusions are based upon the following supporting observations. The treatment of TF mutant strains of Candida cells with BER revealed that HSF1 mutant was most susceptible to this antifungal compound. BER treatment affects the calcineurin pathway and CW integrity leading to dysfunctional mitochondria and cell death. HSF1 levels also impact CW integrity, which is apparent from the susceptibility of HSF1 conditional mutants towards CW inhibitors and from disrupted CW visualized under TEM images. However, unlike BER treatment, the impact of HSF1 on CW integrity was independent of calcineurin stress pathway. For example, neither HSF1 levels could affect the expression of calcineurin pathway genes nor observed dysfunctional mitochondria and enhanced ROS levels following BER treatment were associated with HSF1 phenotype. Although, HSF1 levels potentiate the antifungal activity of BER but its influence in enhancing drug susceptibility adopts different regulatory circuitry as shown in Figure 7. Together, our results show that BER displays its antifungal potential through its ability to impair mitochondrial function, generation of ROS, targeting CW integrity pathway and also affecting heat shock transcription factor HSF1.

Bottom Line: However, unlike BER, HSF1 effect on CW appeared to be independent of MAP kinase and Calcineurin pathway genes.Additionally, unlike hsf1 strain, BER treatment of Candida cells resulted in dysfunctional mitochondria, which was evident from its slow growth in non-fermentative carbon source and poor labeling with mitochondrial membrane potential sensitive probe.Together, our study not only describes the molecular mechanism of BER fungicidal activity but also unravels a new role of evolutionary conserved HSF1, in MDR of Candida.

View Article: PubMed Central - PubMed

Affiliation: School of Life Sciences, Jawaharlal Nehru University, New Delhi, India; Special Centre for Molecular Medicine, Jawaharlal Nehru University, New Delhi, India.

ABSTRACT
Candida albicans causes superficial to systemic infections in immuno-compromised individuals. The concomitant use of fungistatic drugs and the lack of cidal drugs frequently result in strains that could withstand commonly used antifungals, and display multidrug resistance (MDR). In search of novel fungicidals, in this study, we have explored a plant alkaloid berberine (BER) for its antifungal potential. For this, we screened an in-house transcription factor (TF) mutant library of C. albicans strains towards their susceptibility to BER. Our screen of TF mutant strains identified a heat shock factor (HSF1), which has a central role in thermal adaptation, to be most responsive to BER treatment. Interestingly, HSF1 mutant was not only highly susceptible to BER but also displayed collateral susceptibility towards drugs targeting cell wall (CW) and ergosterol biosynthesis. Notably, BER treatment alone could affect the CW integrity as was evident from the growth retardation of MAP kinase and calcineurin pathway mutant strains and transmission electron microscopy. However, unlike BER, HSF1 effect on CW appeared to be independent of MAP kinase and Calcineurin pathway genes. Additionally, unlike hsf1 strain, BER treatment of Candida cells resulted in dysfunctional mitochondria, which was evident from its slow growth in non-fermentative carbon source and poor labeling with mitochondrial membrane potential sensitive probe. This phenotype was reinforced with an enhanced ROS levels coinciding with the up-regulated oxidative stress genes in BER-treated cells. Together, our study not only describes the molecular mechanism of BER fungicidal activity but also unravels a new role of evolutionary conserved HSF1, in MDR of Candida.

Show MeSH
Related in: MedlinePlus